Which AI algorithm is great for mapping between two XML files
The standard tool to work with XML files is XSLT. You may not need AI to solve this problem. But.. you have to learn how to program with XSLT ;)
On Windows you can use MSXML, if you work from C++ - msxsl.exe, C# has internal supoort for XSLT. That is what I know about. There are also non-MS tools.